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</head><body><div id="web_bg"></div><div id="sidebar"><div id="menu-mask"></div><div id="sidebar-menus"><div class="author-avatar"><img class="avatar-img" data-lazy-src="https://qiniu.codekylin.cn/img/20200807181526.jpg" onerror="onerror=null;src='https://qiniu.codekylin.cn/github/img/friend_404.gif'" alt="avatar"/></div><div class="site-data"><div class="data-item is-center"><div class="data-item-link"><a href="/archives/"><div class="headline">文章</div><div class="length-num">362</div></a></div></div><div class="data-item is-center"><div class="data-item-link"><a href="/tags/"><div class="headline">标签</div><div class="length-num">427</div></a></div></div><div class="data-item is-center"><div class="data-item-link"><a href="/categories/"><div class="headline">分类</div><div class="length-num">101</div></a></div></div></div><hr/><div class="menus_items"><div class="menus_item"><a class="site-page" href="/"><i class="fa-fw fa fa-home"></i><span> 首页</span></a></div><div class="menus_item"><a class="site-page" href="/archives/"><i class="fa-fw fa fa-archive"></i><span> 时间轴</span></a></div><div class="menus_item"><a class="site-page" href="/tags/"><i class="fa-fw fa fa-tags"></i><span> 标签</span></a></div><div class="menus_item"><a class="site-page" href="/categories/"><i class="fa-fw fa fa-folder-open"></i><span> 分类</span></a></div><div class="menus_item"><a class="site-page" href="/link/"><i class="fa-fw fa fa-link"></i><span> 友链</span></a></div><div class="menus_item"><a class="site-page" href="/about/"><i class="fa-fw fa fa-heart"></i><span> 关于</span></a></div></div></div></div><div class="post" id="body-wrap"><header class="post-bg" id="page-header" style="background-image: url('https://qiniu.codekylin.cn/github/img/img/wallhaven-4do8mo.jpg')"><nav id="nav"><span id="blog_name"><a id="site-name" href="/">Kylin</a></span><div id="menus"><div id="search-button"><a class="site-page social-icon search"><i class="fas fa-search fa-fw"></i><span> 搜索</span></a></div><div class="menus_items"><div class="menus_item"><a class="site-page" href="/"><i class="fa-fw fa fa-home"></i><span> 首页</span></a></div><div class="menus_item"><a class="site-page" href="/archives/"><i class="fa-fw fa fa-archive"></i><span> 时间轴</span></a></div><div class="menus_item"><a class="site-page" href="/tags/"><i class="fa-fw fa fa-tags"></i><span> 标签</span></a></div><div class="menus_item"><a class="site-page" href="/categories/"><i class="fa-fw fa fa-folder-open"></i><span> 分类</span></a></div><div class="menus_item"><a class="site-page" href="/link/"><i class="fa-fw fa fa-link"></i><span> 友链</span></a></div><div class="menus_item"><a class="site-page" href="/about/"><i class="fa-fw fa fa-heart"></i><span> 关于</span></a></div></div><div id="toggle-menu"><a class="site-page"><i class="fas fa-bars fa-fw"></i></a></div></div></nav><div id="post-info"><h1 class="post-title">Java-IO流-3</h1><div id="post-meta"><div class="meta-firstline"><span class="post-meta-date"><i class="far fa-calendar-alt fa-fw post-meta-icon"></i><span class="post-meta-label">发表于</span><time class="post-meta-date-created" datetime="2019-12-18T06:01:14.000Z" title="发表于 2019-12-18 14:01:14">2019-12-18</time><span class="post-meta-separator">|</span><i class="fas fa-history fa-fw post-meta-icon"></i><span class="post-meta-label">更新于</span><time class="post-meta-date-updated" datetime="2022-07-12T11:42:50.037Z" title="更新于 2022-07-12 19:42:50">2022-07-12</time></span><span class="post-meta-categories"><span class="post-meta-separator">|</span><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/categories/Java/">Java</a><i class="fas fa-angle-right post-meta-separator"></i><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/categories/Java/IO%E6%B5%81/">IO流</a></span></div><div class="meta-secondline"><span class="post-meta-separator">|</span><span class="post-meta-wordcount"><i class="far fa-file-word fa-fw post-meta-icon"></i><span class="post-meta-label">字数总计:</span><span class="word-count">1.6k</span><span class="post-meta-separator">|</span><i class="far fa-clock fa-fw post-meta-icon"></i><span class="post-meta-label">阅读时长:</span><span>6分钟</span></span></div></div></div></header><main class="layout" id="content-inner"><div id="post"><article class="post-content" id="article-container"><h2 id="IO流操作文件"><a href="#IO流操作文件" class="headerlink" title="IO流操作文件"></a>IO流操作文件</h2><ul>
<li><p><strong>创建源 File</strong></p>
</li>
<li><p><strong>选择创建流 InputStream OutputStream Reader Writer</strong></p>
</li>
<li><p><strong>读写操作 write() read()</strong></p>
</li>
<li><p><strong>关闭资源 close()</strong></p>
</li>
</ul>
<h2 id="FileReader"><a href="#FileReader" class="headerlink" title="FileReader"></a>FileReader</h2><p><strong>FileReader类从InputStreamReader类继承而来。该类按字符读取流中数据。可以通过以下几种构造方法创建需要的对象。(输入流 节点流 字符流 )</strong></p>
<p><strong>在给定从中读取数据的 File 的情况下创建一个新 FileReader。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileReader</span><span class="params">(File file)</span></span></span><br></pre></td></tr></table></figure>
<p><strong>在给定从中读取数据的 FileDescriptor 的情况下创建一个新 FileReader。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileReader</span><span class="params">(FileDescriptor fd)</span></span></span><br></pre></td></tr></table></figure>
<p><strong>在给定从中读取数据的文件名的情况下创建一个新 FileReader。查看源码得知，当fileName不为空时，会调用new file（fileName）创建出一个file对象，从而简化代码。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileReader</span><span class="params">(String fileName)</span> </span></span><br></pre></td></tr></table></figure>
<span id="more"></span>

<p><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200516104904.png" alt="">)<img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405110432.png" alt=""></p>
<p><strong>将的hello.txt文件内容读入程序中，并输出到控制台</strong></p>
<p><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405110430.png" alt=""></p>
<p><strong>标准写法</strong></p>
<p><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200405110431.png" alt=""></p>
<h2 id="FileWriter"><a href="#FileWriter" class="headerlink" title="FileWriter"></a>FileWriter</h2><p><strong>FileWriter 类从 OutputStreamWriter 类继承而来。该类按字符向流中写入数据。可以通过以下几种构造方法创建需要的对象。(输出流 字符流 节点流)</strong></p>
<p><strong>在给出 File 对象的情况下构造一个 FileWriter 对象。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileWriter</span><span class="params">(File file)</span></span></span><br></pre></td></tr></table></figure>
<p><strong>在给出 File 对象的情况下构造一个 FileWriter 对象。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileWriter</span><span class="params">(File file, <span class="keyword">boolean</span> append)</span></span></span><br></pre></td></tr></table></figure>
<p>构造与某个文件描述符相关联的 FileWriter 对象。</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileWriter</span><span class="params">(FileDescriptor fd)</span></span></span><br></pre></td></tr></table></figure>
<p><strong>在给出文件名的情况下构造 FileWriter 对象，它具有指示是否挂起写入数据的 boolean 值。</strong></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="title">FileWriter</span><span class="params">(String fileName, <span class="keyword">boolean</span> append)</span></span></span><br></pre></td></tr></table></figure>

<p><strong>File对应的硬盘中的文件如果不存在，在输出的过程中，会自动创建此文件。</strong></p>
<p><strong>append：如果 append 参数为 true，则将字节写入文件末尾处，从原有文件中继续写入，相当于追加信息。如果 append 参数为 false, 则写入文件开始处即对原有文件的覆盖。默认为false</strong></p>
<p><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200516105104.png" alt=""></p>
<h2 id="FileReader和FileWriter的共同使用"><a href="#FileReader和FileWriter的共同使用" class="headerlink" title="FileReader和FileWriter的共同使用"></a>FileReader和FileWriter的共同使用</h2><p><img src= "https://gitee.com/kylincw/images/raw/master/loading.gif" data-lazy-src="https://qiniu.codekylin.cn/img/20200516105117.png" alt=""></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span 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class="line">182</span><br><span class="line">183</span><br><span class="line">184</span><br><span class="line">185</span><br><span class="line">186</span><br><span class="line">187</span><br><span class="line">188</span><br><span class="line">189</span><br><span class="line">190</span><br><span class="line">191</span><br><span class="line">192</span><br><span class="line">193</span><br><span class="line">194</span><br><span class="line">195</span><br><span class="line">196</span><br><span class="line">197</span><br><span class="line">198</span><br><span class="line">199</span><br><span class="line">200</span><br><span class="line">201</span><br><span class="line">202</span><br><span class="line">203</span><br><span class="line">204</span><br><span class="line">205</span><br><span class="line">206</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> org.junit.Test;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> java.io.*;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * 一、流的分类：</span></span><br><span class="line"><span class="comment"> * 1.操作数据单位：字节流、字符流</span></span><br><span class="line"><span class="comment"> * 2.数据的流向：输入流、输出流</span></span><br><span class="line"><span class="comment"> * 3.流的角色：节点流、处理流</span></span><br><span class="line"><span class="comment"> * &lt;p&gt;</span></span><br><span class="line"><span class="comment"> * 二、流的体系结构</span></span><br><span class="line"><span class="comment"> * 抽象基类         节点流（或文件流）                               缓冲流（处理流的一种）</span></span><br><span class="line"><span class="comment"> * InputStream     FileInputStream   (read(byte[] buffer))        BufferedInputStream (read(byte[] buffer))</span></span><br><span class="line"><span class="comment"> * OutputStream    FileOutputStream  (write(byte[] buffer,0,len)  BufferedOutputStream (write(byte[] buffer,0,len) / flush()</span></span><br><span class="line"><span class="comment"> * Reader          FileReader (read(char[] cbuf))                 BufferedReader (read(char[] cbuf) / readLine())</span></span><br><span class="line"><span class="comment"> * Writer          FileWriter (write(char[] cbuf,0,len)           BufferedWriter (write(char[] cbuf,0,len) / flush()</span></span><br><span class="line"><span class="comment"> *</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">FileReaderWriterTest</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">main</span><span class="params">(String[] args)</span> </span>&#123;</span><br><span class="line">        File file = <span class="keyword">new</span> File(<span class="string">&quot;hello.txt&quot;</span>);<span class="comment">//相较于当前工程</span></span><br><span class="line">        System.out.println(file.getAbsolutePath());</span><br><span class="line"></span><br><span class="line">        File file1 = <span class="keyword">new</span> File(<span class="string">&quot;day09\\hello.txt&quot;</span>);</span><br><span class="line">        System.out.println(file1.getAbsolutePath());</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 将的hello.txt文件内容读入程序中，并输出到控制台</span></span><br><span class="line"><span class="comment">     * &lt;p&gt;</span></span><br><span class="line"><span class="comment">     * 说明点：</span></span><br><span class="line"><span class="comment">     * 1. read()的理解：返回读入的一个字符。如果达到文件末尾，返回-1</span></span><br><span class="line"><span class="comment">     * 2. 异常的处理：为了保证流资源一定可以执行关闭操作。需要使用try-catch-finally处理</span></span><br><span class="line"><span class="comment">     * 3. 读入的文件一定要存在，否则就会报FileNotFoundException。</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="meta">@Test</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">testFileReader</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        FileReader fr = <span class="keyword">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">//1.实例化File类的对象，指明要操作的文件</span></span><br><span class="line">            File file = <span class="keyword">new</span> File(<span class="string">&quot;hello.txt&quot;</span>);</span><br><span class="line">            <span class="comment">//2.提供具体的流</span></span><br><span class="line">            fr = <span class="keyword">new</span> FileReader(file);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//3.数据的读入</span></span><br><span class="line">            <span class="comment">//read():返回读入的一个字符。如果到达文件末尾，返回-1</span></span><br><span class="line">            <span class="comment">//方式一：</span></span><br><span class="line"><span class="comment">/*        int data = fr.read();</span></span><br><span class="line"><span class="comment">        while (data != -1) &#123;</span></span><br><span class="line"><span class="comment">            System.out.print((char) data);</span></span><br><span class="line"><span class="comment">            data = fr.read();</span></span><br><span class="line"><span class="comment">        &#125;*/</span></span><br><span class="line"></span><br><span class="line">            <span class="comment">//方式二：语法上针对方式一的修改</span></span><br><span class="line">            <span class="keyword">int</span> data;</span><br><span class="line">            <span class="keyword">while</span> ((data = fr.read()) != -<span class="number">1</span>) &#123;</span><br><span class="line">                System.out.print((<span class="keyword">char</span>) data);</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">//4.流的关闭连接</span></span><br><span class="line">            <span class="keyword">try</span> &#123;</span><br><span class="line">                <span class="keyword">if</span> (fr != <span class="keyword">null</span>) &#123;</span><br><span class="line">                    fr.close();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="comment">//对read()操作升级：使用read的重载方法</span></span><br><span class="line">    <span class="meta">@Test</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">testFileReader1</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        FileReader fr = <span class="keyword">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">//1.File类的实例化</span></span><br><span class="line">            File file = <span class="keyword">new</span> File(<span class="string">&quot;hello.txt&quot;</span>);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//2.FileReader流的实例化</span></span><br><span class="line">            fr = <span class="keyword">new</span> FileReader(file);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//3.读入的操作</span></span><br><span class="line">            <span class="comment">//read(char[] cbuf):返回每次读入cbuf数组中的字符的个数。如果达到文件末尾，返回-1</span></span><br><span class="line">            <span class="keyword">char</span>[] cbuf = <span class="keyword">new</span> <span class="keyword">char</span>[<span class="number">5</span>];</span><br><span class="line">            <span class="keyword">int</span> len;</span><br><span class="line">            <span class="keyword">while</span> ((len = fr.read(cbuf)) != -<span class="number">1</span>) &#123;</span><br><span class="line">                <span class="comment">//方式一：</span></span><br><span class="line">                <span class="comment">//错误的写法</span></span><br><span class="line"><span class="comment">//                for(int i = 0;i &lt; cbuf.length;i++)&#123;</span></span><br><span class="line"><span class="comment">//                    System.out.print(cbuf[i]);</span></span><br><span class="line"><span class="comment">//                &#125;</span></span><br><span class="line">                <span class="comment">//正确的写法</span></span><br><span class="line"><span class="comment">//                for(int i = 0;i &lt; len;i++)&#123;</span></span><br><span class="line"><span class="comment">//                    System.out.print(cbuf[i]);</span></span><br><span class="line"><span class="comment">//                &#125;</span></span><br><span class="line">                <span class="comment">//方式二：</span></span><br><span class="line">                <span class="comment">//错误的写法,对应着方式一的错误的写法</span></span><br><span class="line"><span class="comment">//                String str = new String(cbuf);</span></span><br><span class="line"><span class="comment">//                System.out.print(str);</span></span><br><span class="line">                <span class="comment">//正确的写法</span></span><br><span class="line">                String str = <span class="keyword">new</span> String(cbuf, <span class="number">0</span>, len);</span><br><span class="line">                System.out.print(str);</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (fr != <span class="keyword">null</span>) &#123;</span><br><span class="line">                <span class="comment">//4.资源的关闭</span></span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fr.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line"></span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 从内存中写出数据到硬盘的文件里。</span></span><br><span class="line"><span class="comment">     * &lt;p&gt;</span></span><br><span class="line"><span class="comment">     * 说明：</span></span><br><span class="line"><span class="comment">     * 1. 输出操作，对应的File可以不存在的。并不会报异常</span></span><br><span class="line"><span class="comment">     * 2.</span></span><br><span class="line"><span class="comment">     * File对应的硬盘中的文件如果不存在，在输出的过程中，会自动创建此文件。</span></span><br><span class="line"><span class="comment">     * File对应的硬盘中的文件如果存在：</span></span><br><span class="line"><span class="comment">     * 如果流使用的构造器是：FileWriter(file,false) / FileWriter(file):对原有文件的覆盖</span></span><br><span class="line"><span class="comment">     * 如果流使用的构造器是：FileWriter(file,true):不会对原有文件覆盖，而是在原有文件基础上追加内容</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="meta">@Test</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">testFileWriter</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        FileWriter fw = <span class="keyword">null</span>;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">//1.提供File类的对象，指明写出到的文件</span></span><br><span class="line">            File file = <span class="keyword">new</span> File(<span class="string">&quot;hello1.txt&quot;</span>);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//2.提供FileWriter的对象，用于数据的写出</span></span><br><span class="line">            fw = <span class="keyword">new</span> FileWriter(file, <span class="keyword">true</span>);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//3.写出的操作</span></span><br><span class="line">            fw.write(<span class="string">&quot;I have a dream!\n&quot;</span>);</span><br><span class="line">            fw.write(<span class="string">&quot;you need to have a dream!\n&quot;</span>);</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">//4.流资源的关闭</span></span><br><span class="line">            <span class="keyword">if</span> (fw != <span class="keyword">null</span>) &#123;</span><br><span class="line"></span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fw.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="meta">@Test</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">testFileReaderFileWriter</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        FileReader fr = <span class="keyword">null</span>;</span><br><span class="line">        FileWriter fw = <span class="keyword">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">//1.创建File类的对象，指明读入和写出的文件</span></span><br><span class="line">            File srcFile = <span class="keyword">new</span> File(<span class="string">&quot;hello.txt&quot;</span>);</span><br><span class="line">            File destFile = <span class="keyword">new</span> File(<span class="string">&quot;hello2.txt&quot;</span>);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//不能使用字符流来处理图片等字节数据</span></span><br><span class="line"><span class="comment">//            File srcFile = new File(&quot;爱情与友情.jpg&quot;);</span></span><br><span class="line"><span class="comment">//            File destFile = new File(&quot;爱情与友情1.jpg&quot;);</span></span><br><span class="line"></span><br><span class="line">            <span class="comment">//2.创建输入流和输出流的对象</span></span><br><span class="line">            fr = <span class="keyword">new</span> FileReader(srcFile);</span><br><span class="line">            fw = <span class="keyword">new</span> FileWriter(destFile);</span><br><span class="line"></span><br><span class="line">            <span class="comment">//3.数据的读入和写出操作</span></span><br><span class="line">            <span class="keyword">char</span>[] cbuf = <span class="keyword">new</span> <span class="keyword">char</span>[<span class="number">5</span>];</span><br><span class="line">            <span class="keyword">int</span> len;<span class="comment">//记录每次读入到cbuf数组中的字符的个数</span></span><br><span class="line">            <span class="keyword">while</span> ((len = fr.read(cbuf)) != -<span class="number">1</span>) &#123;</span><br><span class="line">                <span class="comment">//每次写出len个字符</span></span><br><span class="line">                fw.write(cbuf, <span class="number">0</span>, len);</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">//4.关闭流资源</span></span><br><span class="line">            <span class="keyword">try</span> &#123;</span><br><span class="line">                <span class="keyword">if</span> (fw != <span class="keyword">null</span>)</span><br><span class="line">                    fw.close();</span><br><span class="line">            &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line"></span><br><span class="line">            <span class="keyword">try</span> &#123;</span><br><span class="line">                <span class="keyword">if</span> (fr != <span class="keyword">null</span>)</span><br><span class="line">                    fr.close();</span><br><span class="line">            &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span 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